[Qgis-developer] Moving forward with the raster transparency branch

[Peter Ersts]

QGIS Devs,

There has been interest in merging the mods in the 
raster_transparency_branch into the 0.9.1 release. The main changes 
currently are:
1) Revival of basic contrast enhancement
2) Introduction of transparent pixel lists
3) Foundation for basic color ramps.

More information about the raster_transparency_branch can be found here:

http://wiki.qgis.org/qgiswiki/RasterTransparencyBranch

Back in May and June there was a meeting to discuss refactoring of the 
monolithic (5K+ lines) QgsRasterLayer class. The last UML design can be 
found here:

http://wiki.qgis.org/qgiswiki/RasterRefactorRfc

There still needs to be some discussion regarding the final refactoring 
of QgsRasterLayer as there are some great ideas being proposed but 
uncertainty regarding the best approach.

In the mean time, I am proposing that contract enhancement and 
transparency be the first functionality that is broken out of 
QgsRasterLayer, as they are relatively well defined, discrete components 
that are well suited for being separate classes. I will undertake this 
in the current raster_transparency_branch with the goal of having this 
ready for the 0.9.1 release. I propose that classes be named:

QgsRasterTransparencyFilter
QgsRasterContrastEnhancementFilter

I am not sold of the Filter suffix but am still using the June UML as a 
bit of a guide. These changes should not affect anything outside of 
QgsRasterLayer and should not adversely affect anything class that 
inherits QgsRasterLayer.

Please let me know what you think.  Marco, I want to specifically ensure 
that these proposed changes will not impact anything you are currently 
working on. Again, these changes will be made under the 
raster_transparency_branch first, then at a later date merged into the 
trunk.

Thanks
-pete

BTW: from the 12 to the 22 I will have limited access to e-mail, so 
apologies ahead of time if I am slow to respond .

-- 
====================================
Peter J. Ersts, Project Specialist
American Museum of Natural History
Center for Biodiversity and Conservation
Central Park West at 79th Street
New York, New York 10024
Tel: (212)-496-3488 or (212)-769-5742
Fax: (212)-313-7295 or (212)-769-5292
Web: http://cbc.amnh.org
Web: http://geospatial.amnh.org

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